The former head of Israel’s Shin Bet security agency made news yesterday by blasting Israeli Prime Minister Benjamin Netanyhu’s government for exaggerating the effectiveness of a possible military strike on Iran’s nuclear infrastructure.

Yuval Diskin, who retired last year after Netanyahu failed to renew his term in office, cast doubt on Netanyahu’s leadership: “I fear very much that these are not the people I’d want at the wheel.”

What to make of this bitter political attack?

First of all, it is a symptom of Israel’s increasingly polarized political environment in the run-up to the parliamentary elections. Netanyahu is reportedly mulling whether to call for early elections to advance the timetable for elections currently slated for October 2013. It would not be surprising to discover that Diskin harbors political ambitions that he hopes to advance with the public attack.

Secondly, it is another sign, if any more were needed, that Netanyahu is deadly serious about launching a preventive strike against Iran in anticipatory self-defense. Dishkin’s riposte followed criticism from other Israeli security officials who are concerned about the possible fallout from an Israeli military strike. Last week, the chief of staff of the Israel Defense Forces, Lieutenant General Benny Gantz, publicly contradicted Netanyahu’s assessment that Iran’s leaders could not be trusted with a nuclear weapon by opining that they were “very rational” and probably would decide not to build a nuclear weapon.

Last year, Meir Dagan, the former head of the Mossad (who was also retired by Netanyahu), warned that an Israeli strike against Iran’s nuclear facilities would be “stupid” because it would not permanently destroy Iran’s nuclear program and would trigger an unpredictable war. But Netanyahu remains more focused on the dangers of a possible war with a nuclear-armed Iran, a scenario that he has characterized as an unacceptable existential threat to Israel. Whatever Israel eventually decides to do, the United States should back up its ally and closely coordinate policies to prevent Iran from attaining a nuclear weapon.